Chapter 1: Nutrition in Plants & Animals
पादपों एवं प्राणियों में पोषण (प्रकाश संश्लेषण, घटपर्णी एवं पाचन तंत्र)
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- Modes of nutrition: Autotrophic (green plants synthesize food via chlorophyll, sunlight, CO2, water) and Heterotrophic (animals, non-green plants).
- Photosynthesis equation: $6CO_2 + 6H_2O \xrightarrow{\text{Sunlight, Chlorophyll}} C_6H_{12}O_6 + 6O_2$. Oxygen is released into the atmosphere.
- Stomata: Tiny pores on leaf surfaces regulated by guard cells that permit exchange of carbon dioxide and oxygen, and water loss via transpiration.
- Parasitic plants: Cuscuta (Amarbel) lacks chlorophyll; it coils around host trees and absorbs nutrients using haustoria.
- Insectivorous plants: Pitcher plant (Nepenthes), Utricularia, and Venus flytrap grow in nitrogen-deficient soil and trap insects to obtain nitrogen.
- Symbiosis & Lichens: An association between an Alga (which prepares food by photosynthesis) and a Fungus (which provides shelter, water, and minerals).
- Ruminant Digestion: Cows, buffaloes, and deer chew cud. They have a 4-chambered stomach (Rumen, Reticulum, Omasum, Abomasum) containing bacteria that break down cellulose.
- Trap: CBSE states Cuscuta is a saprophyte. Correct: Cuscuta (Amarbel) is a PARASITE (absorbs food from a living host). Fungi (mushrooms) are SAPROPHYTES (feed on dead matter).
- Trap: CBSE states insectivorous plants do not photosynthesize. Correct: Pitcher plants HAVE green chlorophyll and perform photosynthesis, but trap insects solely to satisfy their NITROGEN deficiency.
- Trap: CBSE asks which animal digests cellulose without chewing cud. Correct: Humans cannot digest cellulose because our digestive tract lacks the symbiotic microorganisms found in ruminant stomachs.
NCERT Core Facts: Autotrophic & Heterotrophic Plant Strategies & Human/Ruminant Digestion
Class 7 Science Chapter 1 & 2 forms the backbone of biological science questions in CTET Paper 2.
1. Special Heterotrophic Plant Adaptations
| Plant Category | NCERT Example | Feeding Mechanism |
|---|---|---|
| Parasite | Cuscuta (Amarbel) | Yellow tubular stem with no chlorophyll; wraps around host tree and extracts ready-made food via parasitic roots (haustoria). |
| Insectivorous Plant | Pitcher Plant (*Nepenthes*) | Leaves modified into a jug-like pitcher with a lid. Contains digestive enzymes. Grows in nitrogen-deficient soil; traps insects for nitrogen. |
| Saprotroph | Fungi (Mushroom, Yeast, Bread Mould) | Secretes digestive juices onto dead and decaying organic matter and absorbs dissolved nutrients. |
| Symbiosis | Lichens | Symbiotic partnership between an Alga (chlorophyll-bearing autotroph) and a Fungus (provides shelter and water). |
2. Ruminant Digestive System (Cud-Chewing Animals)
- Herbivorous animals like cows, deer, and buffaloes swallow grass quickly and store it in a specialized stomach chamber called the Rumen.
- In the rumen, food is partially digested into cud.
- Later, the cud returns to the mouth in small lumps and the animal chews it thoroughly.
- Cellulose Digestion: Grass is rich in cellulose. Specialized anaerobic bacteria and protozoa in the rumen and caecum digest cellulose. Humans cannot digest cellulose because we lack these specific enzymes and gut chambers.
Test Your Mastery: Nutrition in Plants & Animals
Authentic CBSE exam questions tested directly from this NCERT chapter.
Which of the following is a parasitic plant that climbs on trees and absorbs ready-made food from the host?
निम्नलिखित में से कौन सा एक परजीवी पौधा है जो पेड़ों पर चढ़ता है और मेजबान से बना-बनाया भोजन अवशोषित करता है?
Lichens represent a symbiotic relationship between which two organisms?
लाइकेन किन दो जीवों के बीच सहजीवी संबंध का प्रतिनिधित्व करते हैं?
Why do insectivorous plants like Nepenthes trap insects if they are green and have chlorophyll?
They grow in waterlogged, nitrogen-deficient soils; they capture insects and digest them to absorb vital nitrogenous compounds.
What is the symbiotic relationship in Lichens?
Lichens consist of an Alga (provides food via photosynthesis) and a Fungus (provides shelter, water, and minerals).
Why can ruminants digest grass while humans cannot?
Ruminants have specialized gut chambers (rumen) containing bacteria capable of breaking down cellulose, which the human digestive tract cannot break down.